Field of the Invention
The present invention relates to a power supplying system, and in particular to an power supplying system with low standby power consumption.
Description of Related Art
Reference is made to FIG. 1, which is a circuit diagram of a related art switch-controlling circuit. The switch-controlling circuit 1 is electrically connected to a direct current (DC) power source VDC and a switching component 10. The switching controlling circuit 1 is configured to control conduction of the switching component 54 so as to decide whether or not the DC power source conduct to an electronic system PS. The electronic system PS is electrically connected to the drain terminal of the switching component 10 via outputting resistor Ro1 and Ro2, and the nodes electrically connected between the electronic system PS and the outputting resistor Ro1 and Ro2 are respectively defined as power outputting terminal Vo1 and Vo2.
The switch-controlling circuit 1 includes a sensing resistor RS, a controlling switch Q, a resistor R, and a capacitor C. One terminal of the sensing resistor RS is electrically connected to the DC power source VDC and the source terminal of the switching component 10, and the other terminal of the sensing resistor RS is electrically connected to the drain terminal of the controlling switch Q and the gate terminal of the switching component 10. The source terminal of the controlling switch Q is electrically connected to the ground, and the gate terminal thereof is electrically connected to a controlling-signal outputting terminal Sin. One terminal of the resistor R is electrically connected to the gate terminal of the controlling switch Q, and the other terminal thereof is electrically connected to the ground. One terminal of the capacitor C is electrically connected to the gate terminal of the controlling switch Q, and the other terminal thereof is electrically connected to the ground. In short, the resistor R and the capacitor C are electrically connected in parallel and are configured to filter noise sent from the controlling-signal outputting terminal Sin.
In the moment of the electronic system PS is activated, the controlling-signal outputting terminal Sin sends a controlling signal to the controlling switch Q to drive the controlling switch Q to conduct (which allowing full current to the sensing resistor RS), and then the switching component 10 conducts. It should be noted that the time difference between the conduction of the controlling switch Q and that of the switching component 10 is quite short, and can be considered that the controlling switch Q and the switching component 10 close at the same time, however which causes the voltage level of the DC power source VDC suddenly dropping, as shown in FIG. 2.